The Cimicidae is a family of blood‐dependent ectoparasites in which dispersion capacity is greatly associated with host movements. Bats are the ancestral and most prevalent hosts for cimicids. Cimicids have a worldwide distribution matching that of their hosts, but the global classification is incomplete, especially for species outside the most common Cimicidae taxa. In this study, we place a little‐studied cimicid species,
Bucimex chilensis
, within a comprehensive molecular phylogeny of Cimicidae by sequencing the genomic regions of this and other closely related species. For this study, we collected
B. chilensis
females from
Myotis chiloensis
in Tierra del Fuego, 1,300 km further south than previously known southernmost distribution boundary. We also sequenced COI regions from
Primicimex cavernis
, a species which together with
B. chilensis
comprise the entire subfamily Primiciminae. Using Bayesian posterior probability and maximum‐likelihood approaches, we found that
B. chilensis
and
P. cavernis
clustered close to each other in the molecular analyses, receiving support from similar morphological features, agreeing with the morphology‐based taxonomic placement of the two species within the subfamily Primiciminae. We also describe a previously unrecognized morphological adaptation of the tarsal structure, which allows the austral bat ectoparasite,
B. chilensis
, to cling on to the pelage of its known host, the Chilean myotis (
Myotis chiloensis
). Through a morphological study and behavioral observation, we elucidate how this tarsal structure operates, and we hypothesize that by clinging in the host pelage,
B. chilensis
is able to disperse effectively to new areas despite low host density. This is a unique feature shared by
P. cavernis
, the only other species in Primiciminae.